cutting a carbide rod

[Steve Tiedman]

This 5/16" x 6", 92 Rockwell hardness carbide rod showed up at my shop. Bought through Amazon, but it is sold by Taylor Toolworks. (This little rod weighs 4 ounces- it's some hard, dense steel.)

Unhandled 5/16" x 6" Solid Carbide Cabinet Scraper Burnisher HRC 92-94

A cabinet scraper is a simple, old-world tool that has many uses in the modern woodshop. A well-tuned cabinet scraper can remove glue, tame tearout, refining a finish, or put a glass-smooth finish on wood. Creating a proper cabinet scraper edge (referred to as a hook or burr) is an important...

taytools.com

See that little dark line half way down the length? That's the result of one minute of using a standard Dremel cutoff wheel on it. All it did was polish the surface, can't even feel it with a fingernail.

Anyway, I thought I would cut it in half, make 2 handles to mount them in, and I'd have two scraper burnishers for the price of one. (Lee Valley/Veritas already makes exactly what I'm trying to accomplish...)

Will a diamond Dremel cutoff wheel cut through this solid carbide?

If it's more trouble to cut it than it's worth, I'll just mount this rod about 2" deep into a handle and call it a day. Thanks.

 

[Bill Alston]

Diamond should cut it. If you’re careful, notch it all the way round then snap it in half?

 

[Neil S]

View attachment 72102


Will a diamond Dremel cutoff wheel cut through this solid carbide?

Yes, but you may go through a few Dremel diamond cut off wheels before you can cleanly snap apart. A continuous rim (not notched) diamond wheel (typically used for tile cutting) mounted on an angle grinder will do the job quicker. Most hardware shops sell those diamond discs. For a neat job mount the carbide rod in your lathe chuck and use the toolrest on the lathe to control the feed rate of the cut.



Then, if you would like an Acc-Burr style burnisher, with the rod still mounted in the chuck and spinning, make some customised card scraper 'grooves', starting with the diamond cut off wheel and then if necessary finesse and smooth the grooves with Dremel diamond points/wheels...

Accu-Burr ™ Dual-Sided Carbide Scraper Burnisher Patent Pending (DCE)

The Patent Pending Accu-Burr ™ Carbide Burnisher is a game changer when it comes to turning precise, consistent, and effective hooks (or burrs) on cabinet scrapers. No burnisher will produce better results with less effort and less skill. Guaranteed. This completely new type of burnisher is a...

taytools.com

For an even better polished grooves than on the Acc-Burr, you can do that with diamond paste (its relatively cheap now), although I'm not sure if a highly polished groove would be better option than a slightly toothy groove, but you can always experiment with that.

Here is an example of a polish surface on carbide...



Wear eye protection (carbide is hard but brittle) and respiratory protection (carbide contains cobalt).

If I was making one for myself I would put handles on both ends of the 6" rod for an even pull along the scraper edge and have multiple grooves of different sizes and profiles along the rod for what I was wanting to do with the scraper. Derek Cohen made a nice double handled one for his rod...

 

[Steve Tiedman]

Diamond wheel it is.

And I already own an Accu-Burr.

Thanks.

 

[Otis Kiehl]

If you have a 4 1/2” grinder with a thin cut off wheel you should be able to cut it

 

[Dean Center]

I got a 4 pack of carbide rods, 2" or so in length, from Amazon, for anyone considering this project. Ready to insert, inexpensive. Give 1 to each of a couple friends.

EDIT: this is what I bought. Not currently available, but probably someone else is selling similar.
https://www.amazon.com/gp/product/B07BNYZ224/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&psc=1

 

[Bill Alston]

Just as a point of interest, I bought one of these and mounted it in a block of steel.

 

[Steve Tiedman]

Thanks Bill. LV has a longer one for 1/2" scrapers for their plate device, which I do own, but the shipping cost as much as the part. That bugged me too much, so I passed on it.

Dean- I should have kept scrolling at Amazon for those shorter rods that you bought! They would have been about right.

I just picked up a no-name Dremel size diamond cutoff wheel kit (5 diamond discs and a mandrel) for $6 from my local Menards. I'll give this a go. I'll do it outside with the wind blowing away from me to avoid the dust.

 

[hughie]

I think the cutting is one aspect, but the shaping might prove to be the biggest challenge.

 

[Steve Tiedman]

Well, that was fun. The little diamond cutoff wheel was working- very slowly. So I put a fresh 4" general purpose cutoff wheel in my angle grinder and went at it. After several minutes, it made the grove shown as the dark, smooth patches on each stick. Did the same for just a minute or two from the other side. Then I put a steel cheater pipe over it, the fulcrum point right at the cut groove, and they snapped right apart. I then lightly dressed off and sharp edges on the cbn bench grinder wheel. Now I'll make a couple handles and I'll be in business.

Moral of the story- buy carbide rod in a length that will work for your project without needing to be cut to size.


This is what I am mimicking. Thicker rod, and it will project out a little further.

https://www.leevalley.com/en-us/shop/tools/sharpening/32643-veritas-carbide-burnisher

And this, but from carbide rather than M42.

M42 Burnisher For Best Scraper Burr | Tomasic Woodturning

High quallity burnisher made from M42 cryo rod wraped in ash or sapele mahagony.Rods and ferrule are made in Sheffield by Crown and handles are made by me. Enhance your woodturning scraper performance with the M42 Burnisher.

www.tomasicwoodturning.com

Fun fact- 25 years ago a fella in the local turning club gave me a burned out engine intake valve, to use the stem of the valve for the same purpose. Still have that around here somewhere...

 

[John Whitley]

On the topic of not having to cut carbide, Eric Lofstrom has an interesting solution to carbide for a handheld burnisher: use smaller diameter rod (in principle, for higher force at the point of contact with the tool), conveniently in the form of an upside down Dremel carbide bit. For example, this one on Amazon, for just under $10. Make a slightly undersized hole in your handle, and basically just screw it in. A dab of your favorite adhesive is optional. The burnisher on the left is the result. (The one on the right, for comparison, is from Alan Lacer's burnisher kit which uses 3/8" carbide rod.)

 

[Steve Tiedman]

Brilliant! After the fact.

 

[Steve Tiedman]

I'm not sure it makes a lot of difference, but this is what I wanted the carbide rod for, to burnish/roll hooks on the 4 new Carter M42 scrapers I've bought. The M42 is hard stuff, but the carbide is far harder and should have no issue rolling up a hook. This one started off as their standard dome-style bowl scraper, 1" wide and 1/2" thick, with a factory 80 degree bevel, which I reground to 55 degrees to start with. If needed, like the thickness getting in the way on small work, I'll relieve the bevel heel a few more degrees. Photos below.

Between a new 80 grit ceramic sanding belt (which is pretty much DOA now), a 60 grit al. oxide grinding wheel, and a 180 grit cbn, it took over 2 hours of reshaping time (gotta stop and cool every few minutes) to get to the Raffan-inspired Tomasic "Refiner" scraper profile with the little cutting notch on the left. (Ignore the top right corner, that's the remnants of the factory grind. No need to waste more time and steel chasing that, it'll harmlessly go away with time.) Here is an in-depth Tomislav Tomasic video about his refiner scraper. I skip to about the 10 minute mark to go past product intro news from a few months ago.

View: https://youtu.be/_ly7WJUsq7M?t=595&si=3slUb4apITVNCryS



Ignore the goofy scratch pattern on the bevel below. I knocked the photo file size way down and it killed the resolution of the 180 grit cbn scratch pattern.

 

[John K Jordan]

use smaller diameter rod (in principle, for higher force at the point of contact with the tool),

Good thing to for people to know. My burnishing has evolved through three sizes of carbide rods, the fist was a larger diameter.

This was the large one I used at first many years ago, then I got a number of smaller diameter rods (from a great woodturner who bought them in bulk to get them for less than $2 each) so I made a bunch of burnishers to give away:



What I like by far is the combination of a small carbide rod and a TINY carbide rod. The second is in the form of a carbide triangle (for strength) but the burnishing edge of the triangle is actually a quite small and very smooth radius. This allows a LOT of pressure at a small contact point where needed, or a more reasonable amount of pressure with a lighter touch. Some other nice features: a great handle and the burnishing rods are angled just right for use with the curved hand scrapers I use a lot (work well with NRS too).



As I mentioned in another thread, these were unavailable for a long time so when they finally were available again I bought a spare for "just in case!)

Amazon.com

(I see they are the same price as last Sept)

JKJ

 

[Steve Tiedman]

Okay, I accept and understand the smaller diameter carbide rod concentrating the contact patch, and also the psi at the point of contact, but realistically, the arbitrary 5/16" diameter I'm using, vs. 1/8" or 3/16" diameter, either way it is still two small convex shapes of incredibly hard material (i.e. no deflection in comparison to wood, rubber, etc.) touching at a very small contact patch/point. Are we sure it's not almost a placebo effect in saying the relatively smaller rod will roll the same hook with a relatively dramatic lesser amount of force? Data? I think it is safe to say that any burnisher mfr. is going to use the smallest piece of material that still does the job the same way as a larger piece of material- it's cheaper to do so. (Now, I'm just asking for the sake of fun, I'm not going to abandon anything I'm doing at this point.)

 

[Steve Tiedman]

5/16" circle has a .982" circumference. Divided by 360 degrees, each one arc degree is .0027" long.

1/8" circle has a .393 circumference. Divided by 360 degrees, each one arc degree is .0011" long. And each of these is still just that, an arc, not a straight line. John's triangular burnisher, if the triangle faces are flat, will have more surface contact on the scraper edge than any of these round shapes.

I hope I did this correctly, mathematics was never a strong suit of mine. But we know that the entire length of one degree arc of either of these burnisher diameters won't be in full contact with the scraper edge, it will be some smaller length, down in the minutes or seconds of degree arc.

I'll contend (for fun, not debate, nor arguement) that burnishers shown in this thread, even the 3/8" diameter Lacer unit mentioned, will all put the same amount of contact length on the edge of the scraper, or certainly not more that ten thou of difference. Essentially, a singular point of contact, not an arc/length of contact. So, use what you've got, they all (likely) work the same.

What are they saying here? Huh? (That's me in high school algebra and geometry classes.)

Solution | Can we show that these two circles touch? | Circles | Underground Mathematics

Section Solution from a resource entitled Can we show that these two circles touch?.

undergroundmathematics.org

 

[Steve Tiedman]

Sometimes I'm just a lazy procrastinator. Tossing around the shop since February, glued but otherwise unrefined and unfinished, are my two carbide rod burnishers. Today I finally made them pretty. 6.75" long total (5" handle incl. ferrule), max. diameter 15/16" (arbitrary, but they feel good in the hand), figured maple handles with copper pipe ferrules, Tried and True finish. The 5/16" carbide extends 1.75" from the handle. The ugly cut end of the carbide is inside the handle. I'll keep one at each lathe. @Dean Center has a better carbide rod version in his message above- no cutting required.

 

[robo hippy]

I think most of the time when cutting carbide, you cut part way through, put it in a vice, and then with a towel over it to prevent shrapnel from flying into your hands, and then snap it in half. Years ago, I bought 100 carbide rods that were 3/16 diameter. Can't remember.... They were perfect size for burnishers. My first one was a carbide drill bit, and others have used old router bits. I do like smaller diameter rather than larger. When I first started burnishing burrs on my tools, which were all M2 at that time, I had some mini carbide bits that I drilled into a steel handle. It worked fine. A standard triangle burnisher for card scrapers did work on M2, but with the round rod, it was difficult to say the least. With M42 or V10, you need carbide. I would expect that carbide will burnisher that StewMac scraper that some use, and they don't tell you what kind of metal it is....

robo hippy

 

[John K Jordan]

I would expect that carbide will burnisher that StewMac scraper that some use, and they don't tell you what kind of metal it is....

The StewMac scrapers don't get a burnished burr, but rely on a hollow-ground on the thick edge to make very sharp "corners" on the upper and lower flat faces. They recommend grinding using a small diameter wheel but I found they work fine with a 8" dia 600 grit CBN wheel.

Not cheap, but incredible hand scrapers. (I don't recommend the one on the right for most woodturning. I ground one corner round for a special use and may reshape the rest of it some day. I wish I knew the type of steel.



JKJ

 

[robo hippy]

I did see a video about them years ago, and the guy showing them commented that you could not burnish a burr on them. I would bet you can with a carbide rod. They do not state what kind of metal it is. If it is steel of any kind, then you can put a burr on it. I did find it funny the way he sharpened them. With an 8 inch wheel, the amount of "concave" would almost be unmeasurable.

robo hippy

 

[Steve Tiedman]

I did see a video about them years ago, and the guy showing them commented that you could not burnish a burr on them. I would bet you can with a carbide rod. They do not state what kind of metal it is. If it is steel of any kind, then you can put a burr on it. I did find it funny the way he sharpened them. With an 8 inch wheel, the amount of "concave" would almost be unmeasurable.

robo hippy

I looked at those when John first posted them. StewMac sells a 5" grinder they say is best for that scraper to create the concave edge. Yep, then the video shows the large wheel being used.

If one has a spare grinder around the shop, Norton makes several smaller diameter wheels (incl. 5") that would suit these scrapers.

 

[John K Jordan]

With an 8 inch wheel, the amount of "concave" would almost be unmeasurable.

Might not be optimum but the concavity on the thick scraper is easy to see and feel. Odd thing, even with the 8" wheel it works extremely well, actually amazingly so.

I use the StewMac scrapers a lot on the inside and outside of bowls and platters and such. Both sides are scraping edges. I made a small setting jig to get the grinding table on the Varigrind exactly right. The steel must be good since the sharp edge lasts a long time, much longer than a burnished burr on a card scraper. (Although I use both kinds of scrapers, sometimes for different reasons.) I can often go directly to 600 grit sanding by hand, depending on the wood. (All dry wood, of course.)

That said, I'm trying to justify buying StewMac's special grinder. But even with an 8' SS table I'm kind of out of space at my sharpening station...



These work so well I sometimes get lazy with the lathe tools in some situations knowing I can smooth perfectly with very little effort.
Just a few weeks ago I followed hollowing with a Hunter tool with the curved end of the small StewMac on the tight insides of this (by hand with lathe off). The surface was perfect with just a few minutes of scraping, even with the very hard dry Persimmon wood, followed by 400/600 grit and "danish" oil.



I'm a believer. If it's good enough for cellos and high-end guitars, it should be good for woodturning.

I looked at those when John first posted them. StewMac sells a 5" grinder they say is best for that scraper to create the concave edge. Yep, then the video shows the large wheel being used.

Just for the record, according to this the grinding wheel is 3" diameter:

Mini Grinder for Ultimate Scrapers - StewMac

Fast, simple sharpening for our Ultimate Scrapers (and more!)

www.stewmac.com

Maybe they now offer a different grinder than before.

JKJ

 

[Steve Tiedman]

Whoops, 3". Thanks John.